|Length||Up to 150 mi (240 km)|
|Width||20 m (66 ft)|
|Height||2.5 m (8 ft 2 in)|
|Completion date||8th century|
Offa's Dyke (Welsh: Clawdd Offa) is a large linear earthwork that roughly follows the current border between England and Wales. The structure is named after Offa, the 8th century king of Mercia, who is traditionally believed to have ordered its construction. Although its precise original purpose is debated, it delineated the border between Anglian Mercia and the Welsh kingdom of Powys.
The Dyke, which was up to 65 feet (20 m) wide (including its flanking ditch) and 8 feet (2.4 m) high, traversed low ground, hills and rivers. Today the earthwork is protected as a scheduled monument. Some of its route is followed by the Offa's Dyke Path; a 176 mi (283 km) long-distance footpath that runs between Liverpool Bay in the north and the Severn Estuary in the south.
Although the Dyke is conventionally dated to the Early Middle Ages of Anglo-Saxon England, research in recent decades - using techniques such as radioactive carbon dating - has challenged the conventional historiography and theories about the earthwork.
The generally accepted theory about much of the earthwork attributes its construction to Offa, King of Mercia from 757 to 796. The structure did not represent a mutually-agreed boundary between the Mercians and the Kingdom of Powys. It had a ditch on the Welsh (western) side, with the displaced soil piled into a bank on the Mercian (eastern) side. This suggests that Mercians constructed it as a defensive earthwork, or to demonstrate the power and intent of their kingdom.
Throughout its entire length, the Dyke constantly provides an uninterrupted view from Mercia into Wales. Where the earthwork encounters hills or high ground, it passes to the west of them.
Although historians often overlook Offa's reign due to limitations in source material, he ranks as one of the greatest Anglo-Saxon rulers - as evidenced in his ability to raise the workforce and resources required to construct Offa's Dyke. The construction of the earthwork probably involved a corvée system requiring vassals to build certain lengths of the earthwork for Offa in addition to the normal services that they provided to their king. The Tribal Hidage, a primary document, shows the distribution of land within 8th century Britain; it shows that peoples were located within specified territories for administration.
The first historians and archaeologists to seriously examine the Dyke juxtaposed their conclusions with the early 10th-century writer Asser, who wrote: "there was in Mercia in fairly recent time a certain vigorous king called Offa, who terrified all the neighbouring kings and provinces around him, and who had a great dyke built between Wales and Mercia from sea to sea".  In 1955 Sir Cyril Fox published the first major survey of the Dyke.  He concurred with Asser that the earthwork ran 'from sea to sea', theorising that the Dyke ran from the River Dee estuary in the north to the River Wye in the south: approximately 150 mi (240 km). Although Fox observed that Offa's Dyke was not a continuous linear structure, he concluded that earthworks were raised in only those areas where natural barriers did not already exist.
Sir Frank Stenton, the UK's most eminent 20th-century scholar on Anglo-Saxon England, accepted Fox's conclusions. He wrote the introduction to Fox's account of the Dyke. Although Fox's work has now been revised to some extent, it still remains a vital record of some stretches of Offa's Dyke that still existed between 1926 and 1928, when his three field surveys took place, but have since been destroyed.
In 1978, Dr Frank Noble challenged some of Fox's conclusions, stirring up new academic interest in Offa's Dyke. His MPhil thesis entitled "Offa's Dyke Reviewed" (1978) raised several questions concerning the accepted historiography of Offa's Dyke. Noble postulated that the gaps in the Dyke were not due to the incorporation of natural features as defensive barriers, but instead the gaps were a "ridden boundary", perhaps incorporating palisades, that left no archaeological trace. Noble also helped establish the Offa's Dyke Association, which maintains the Offa's Dyke Path. This long distance footpath mostly follows the route of the dyke, and is a designated British National Trail.
Ongoing research and archaeology on Offa's Dyke has been undertaken for many years by the Extra-Mural Department of the University of Manchester. Most recently David Hill and Margaret Worthington have undertaken considerable research on the Dyke. Their work, though far from finished, has demonstrated that there is little evidence for the Dyke stretching from sea to sea. Rather, they claim that it is a shorter structure stretching from Rushock Hill north of the Herefordshire Plain to Llanfynydd, near Mold, Flintshire, some 64 miles (103 km). According to Hill and Worthington, dykes in the far north and south may have different dates, and though they may be connected with Offa's Dyke, there is as yet no compelling evidence behind this. However, not all experts accept this view.
The Roman historian Eutropius in his book, Historiae Romanae Breviarium, written around 369, mentions the Wall of Severus, a structure built by Septimius Severus who was Roman Emperor between 193 and 211:
Novissimum bellum in Britannia habuit, utque receptas provincias omni securitate muniret, vallum per CXXXIII passuum milia a mari ad mare deduxit. Decessit Eboraci admodum senex, imperii anno sexto decimo, mense tertio. Historiae Romanae Breviarium, viii 19.1
He had his most recent war in Britain, and to fortify the conquered provinces with all security, he built a wall for 133 miles from sea to sea. He died at York, a reasonably old man, in the sixteenth year and third month of his reign.
This source is conventionally thought to be referring, in error, to either Hadrian's Wall, 73 miles (117 km), or the Antonine Wall, 37 miles (60 km), which were both shorter and built in the 2nd century. Recently, some writers have suggested that Eutropius may have been referring to the earthwork later called Offa's Dyke. Most archaeologists reject this theory.
Evidence has been found that challenges the accepted date of the Dyke's construction. In December 1999, Shropshire County Council archaeologists uncovered the remains of a hearth or fire on the original ground surface beneath Wat's Dyke near Oswestry, England. Carbon dating analysis of the burnt charcoal and burnt clay in situ showed it was covered by earth on or around AD 446. Archaeologists concluded that this part of Wat's Dyke, so long thought of as Anglo-Saxon and a mid-8th-century contemporary of Offa's Dyke, must have been built 300 years earlier in the post-Roman period.
In 2014, excavations by the Clwyd-Powys Archaeological Trust focused on nine samples of the Dyke near Chirk. Radio carbon dating of redeposited turf placed the construction between the years 541 and 651, and lower layers of construction are dated to as early as 430. This evidence suggests that the Dyke may have been a long-term project by several Mercian kings.
The England-Wales border still mostly passes within a few miles of the course of Offa's Dyke through the Welsh Marches. A 3 mi (4.8 km) section of the Dyke, which overlooks Tintern Abbey and includes the Devil's Pulpit near Chepstow, is now managed by English Heritage.
All sections of Offa's Dyke which survive as visible earthworks, or as infilled but undeveloped ditch, are designated as a Scheduled Monument. However, some parts of the Dyke may also remain buried under later development. Some sections are also defined as Sites of Special Scientific Interest, including stretches within the Lower Wye Valley SSSI and the Highbury Wood National Nature Reserve. Parts are located within the Wye Valley and Shropshire Hills Areas of Outstanding Natural Beauty. Most of the line of Offa's Dyke is designated as a Public Right of Way, including those sections which form part of the Offa's Dyke Path.
In August 2013, a 45 m (148 ft) section of Dyke, between Chirk and Llangollen, was destroyed by a local landowner. The destruction of the Dyke to build a stables was said to be like "driving a road through Stonehenge".
Candidate World Heritage Site
Offa’s Dyke is a victim of its very scale, nature, meaning and historical success. It is located in two countries, six local authority areas, multiple ownerships and multiple land-use contexts. The main professional stakeholders – such as the English and Welsh path and heritage management agencies – are organisationally and functionally separate. The ancient monument is now often seen as secondary to the modern path, and heritage advice about individual dyke sections is not generally coordinated via any connected overview of the values of the whole monument. Moreover, despite the lasting legacy of Offa's Dyke for English and Welsh communities alike, there is limited public awareness of the monument and its remarkable link to modern ideas of national identity.
The proposal was rejected in 2011.
The Offa's Dyke Centre
The Offa's Dyke Centre is a purpose-built information centre in the town of Knighton, situated on Offa's Dyke on the border between England (Shropshire) and Wales (Powys). Some of the best remains of the earthworks can be seen within a two-minute walk from the centre.
Offa's Dyke Path
The Offa's Dyke Path (Welsh: Llwybr Clawdd Offa) is a long distance footpath close to the England–Wales border. Although large sections are close to the Dyke itself, the Path is longer, and in some places passes at some distance from the earthworks. Opened in 1971, the Path is one of Britain's longest National Trails, stretching for 283 km (176 mi) from the Severn estuary at Sedbury, near Chepstow, to Prestatyn on the north Wales coast. There is a visitor centre at Prestatyn.
[It] was customary for the English to cut off the ears of every Welshman who was found to the east of the dyke, and for the Welsh to hang every Englishman whom they found to the west of it.
- England and Wales
- England–Wales border
- Wat's Dyke
- Scots' Dike
- Götavirke (Geatish Dyke)
- Danevirke (Danish Dyke)
- Black Pig's Dyke
- Silesia Walls
- Asser, Life of Alfred, p. .14
- Fox 1955
- Ian Bapty review of Hill and Worthington, Offa's Dyke: History and Guide, 2003
- Smith, William (1875). Dictionary of Greek and Roman Antiquities. London: John Murray. p. 762.
Eutropius uses the figure cxxxii (132) milia passuum. As a Roman mile ≈1,479 metres (4,852 ft), 132 Roman miles = 195 km (or 121 statute miles); Offa's Dyke is around 192 km long (a little over 119 statute miles).
- Steve Blake and Scott Lloyd, The Keys To Avalon, Element Books, 2000, ISBN 1-86204-735-9
- CPAT: New book claims that Offa's Dyke is Roman!, article by Ian Bapty
- "What is Offa's Dyke?". The Clwyd-Powys Archaeological Trust. 16 October 2009.
- Matthews, Keith. "Was Offa's Dyke actually the 'Wall of Severus'".
- "Latest thinking about OFFA'S and WAT'S DYKES". New Welsh Review 52. 16 October 2009.
- Hannaford, H.R (1999). Archaeological Investigation on Wat's Dyke at Maes-y-Clawdd, Oswestry. Archaeology Service, Shropshire County Council.
"The excavation produced some residual deposits of worn sherds of Roman Samian ware and coarseware pottery. The report suggests that the dyke should be 'regarded as being contemporary with the other great 5th century linear earthwork, the Wansdyke in Wiltshire . . . an achievement of the post-Roman kingdom of the northern Cornovii, rather than a work of 7th–8th century Mercia.' However Dr David Hill, Senior Research Fellow, Centre for Angio-Saxon Studies, University of Manchester ('Offa Versus The Welsh' – British Archaeoiogy, December 2000) has argued for a date later than the 6th century for Wat's Dyke – that it was constructed as Gwynedd and North Powys briefly became a unified state. Evidence from both dykes suggests, he says, that people were not settling or spending much time in these 'wild zones'."
- "Offa's Dyke: built by multiple kings?". Current Archaeology. XXV, No. 3 (291): 6. June 2014.
- "UK Tentative List of Potential Sites for World Heritage Nomination: Application form: Offa's Dyke", Department for Culture, Media and Sport. Retrieved 3 August 2014
- "Allowed to bulldoze Offa's Dyke... because he claimed didn't know it was there!". Wales Online. 4 June 2014.
- Nathan Rowden, "Offa's Dyke misses out on audacious heritage bid", County Times, 29 March 2011. Retrieved 3 August 2014
- "Offa's Dyke Path". Retrieved 6 April 2012.
- George Borrow, Wild Wales (from folklore)
- Cyril Fox, Offa's Dyke: a Field Survey of the Western Frontier Works of Mercia in the Seventh and Eighth Centuries AD (London, 1955)
- David Hill and Margaret Worthington, Offa's Dyke: History and Guide (Stroud, 2003)
- Frank Noble, Offa's Dyke Reviewed, MPhil thesis Open University (1978). Partly published in Offa's Dyke Reviewed, ed. Margaret Gelling (Oxford, 1983)
- Tyler, D.J. "Offa’s Dyke: a historiographical appraisal," Journal of Medieval History (2011) 37#2 pp 145–161
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|Wikisource has the text of the 1921 Collier's Encyclopedia article Offa's Dyke.|